Twin anemia-polycythemia sequence (TAPS) is characterized by the transfer of blood via intertwin vascular anastomoses in a single placenta. It differs from twin-twin transfusion syndrome (TTTS) in that amniotic fluid levels remain normal during pregnancy. Since the concept of TAPS was first introduced in 2007, some cases have been reported abroad, but no such a case has been reported in Korea. Here, we report the first case of spontaneous TAPS in Korea.